I had a Vaillant combi boiler & programmable room thermostat fitted at the start of the year. The heating is on after the summer and I am left wondering the age old question - is it more economical (and more efficient?) to set the thermostat at a comfortable room temperature throughout the day (and night?) even if I'm in and out of the house OR should I set several programmes of different temperatues eg 1) night 2) day 3) evening?

If, following on from a cooler night time setting, the boiler has to work hard to attain the day time temp I've set rather than just carry on maintaining ONE day/night temp. is this less economical and efficient?

If you suggest it's more economical to maintain the same temp throughout night and day I could keep the bedrooms cooler using the rad. thermostats.

Economics is the main reason for asking but also maintaining the efficiency of the boiler.

It's all down to personal choice/preference, I've never heard or seen of a definitive answer. Air Source and Ground Source heating systems don't get as hot as a typical heating system, therefore the radiators are oversized and are best used 24/7. I used my gas heating system like this last year, as my wife and 2 children were at home most days. This year my wife is back at work and the children are at school/nursery so we're using the heating on timed for a couple of hours before we leave the house and a few hours in the evening. I didn't take any notice of the cost last year - maybe I should have it would have been interesting to see the price difference.